LC HCAL Absorber (SS vs W) and P-Flow P Performance (Scintillator( vs RPC) Comparisons. Motivation. SS/W Absorbers : Single Pion Results

Transcription

1 LC HCAL Absorber (SS vs W) and P-Flow P Performance (Scintillator( vs RPC) Comparisons Steve Magill Steve Kuhlmann ANL/SLAC Motivation SS/W Absorbers : Single Pion Results Analog (Scintillator) vs Digital (RPC) Detector Comparisons P-Flow Analyses : e+e- -> Z (jets) Summary

2 Motivation for Study Can the outer radius of the HCAL be reduced? -> make B-field volume smaller -> saves cost of magnet coil BR 2 Keep 4 λ I thickness of HCAL -> use a denser absorber than SS, i.e., W -> why does SD HCAL have 1 X 0 sampling? -> change to 0.07 λ I (2 X 0 ) sampling in HCAL (already proposal to double the sampling in the last 10 ECAL layers to 1.4 X 0 ) Effects on PFAs, Calorimeter performance? Present SD (SS/Scin) 0.07 λ I W -> 0.7 cm/layer 1 cm Scintillator 4 λ I requires 55 layers -> 93.5 cm from HCAL IR to OR 1 X 0 SS -> 2.0 cm/layer 1 cm Scintillator 4 λ I requires 34 layers -> 102 cm from HCAL IR to OR.5 cm scintillator -> 66 cm from HCAL IR to OR.5 cm scintillator -> 85 cm from HCAL IR to OR

3 Z jets in SS/W HCAL SD SS HCAL SD W HCAL ~0.9 m ~1 m 34 layers 2 cm SS (1 X 0 ) 1 cm Scintillator 4 λ I 55 layers 0.7 cm W (2 X 0 ) 1 cm Scintillator 4 λ I Same event - different shower shape in W compared to SS?

4 Single 5 GeV Pion E measurement with DHCAL SS W Energy measurement in calorimeter Analog ECAL, Digital HCAL -> σ/mean smaller in W HCAL -> same behavior for analog HCAL, but smaller effect... Why?

5 Single 5 GeV Pion Number of hits (1/3 mip thresh) SS W More hits in W HCAL than in SS -> 30% more hits in the HCAL for W -> better digital resolution for W!

6 Single 5 GeV Pion Linearity of hits vs E (HCAL) SS W Both exhibit linear behavior for number of hits vs energy -> more hits per GeV in W

7 Single 5 GeV Pion Visible Energy in HCAL SS W More visible energy in W HCAL

8 Single 5 GeV Pion First Interaction Layer SS W 14 more layers 30 more layers 60 cm into SS HCAL 42 cm into W HCAL

9 Single 5 GeV Pion Shower Shape Analysis SS cone mean (GeV) rms σ/mean χ W cone mean (GeV) rms σ/mean χ rms Energy in fixed cone size : -> means ~same for SS/W -> rms ~10% smaller in W cone Tighter showers in W

10 Summary of Single Pion Results Energy versus fixed cone size -> means very similar for SS/W... however, the rms in the W HCAL was ~10% smaller than the SS CAL Energy Sums -> for analog energy sum with 1/3 mip threshold in the HCAL, sigma/mean is ~14% smaller in the W HCAL -> for ECAL analog and HCAL digital - again, the sigma/mean was smaller in the W HCAL -> for HCAL only when the pions deposited only mips in the ECAL, sigma/mean ~10% smaller in the W HCAL CAL Number of Hits -> total number of hits in the CAL, counting hits in ECAL and HCAL with a 1/3 mip threshold in the HCAL was 108 in W, 94 in SS -> in HCAL alone, 46 in W, 35 in SS (30% more in W) 1) More hits and visible energy -> better digital and analog E resolution 2) Tighter showers -> better PFA performance? 3) All of the above in smaller B-field volume -> R 2 cost savings

11 Track Extrapolation Particle-flow Algorithm ANL, SLAC 1 st step - Track extrapolation thru Cal substitute for Cal cells (mip + ECAL shower cone + HCAL cone : reconstruct linked mip segments + iterated in E/p hits in cones) - analog or digital techniques in HCAL Cal granularity/segmentation optimized for separation of charged/neutral clusters 2 nd step - Photon finder - use analytic long./trans. energy profiles, ECAL shower max, etc. 3 rd step - Jet Algorithm - tracks + photons + remaining Cal cells in jet cones defined by charged track jets (neutral hadron contribution) - Cal clustering not needed -> Digital HCAL?

12 e+e- -> > Z (jets) Energy Sums in Calorimeter SS W Total CAL energy sum tighter with W HCAL -> better analog E resolution

13 e+e- -> > Z (jets) Number of hits in Calorimeter SS W ~ 35% more hits in W HCAL than SS -> better digital E resolution

14 e+e- -> > Z (jets) PFA performance SS W True PFA -> SS 33%/ E -> W 28%/ E Compare current PFA with true... Fit ->

15 e+e- -> > Z (jets) PFA performance Fits SS W Better PFA performance with the W HCAL for conical showers... however, simple iterative cone reconstructs smaller fraction of events* * Improve with neutral clustering?

16 Summary of PFA Results HCAL Absorber Material -> dense absorber is optimal for LC HCAL -> single particle analog and digital E resolutions improved with W compared to SS (more hits and visible E per volume) -> better sampling in W HCAL (7% compared to 12% of λ I per layer) -> PFA performance not compromised with a shorter, denser HCAL (in fact, improved!) -> major cost savings if magnetic coil radius can be reduced -> last 10 layers of ECAL will sample at 1.4 X 0 (0.5 cm W absorber) -> using W for absorber with 2 X 0 sampling (more accurately, 0.07 λ I sampling) improves PFA performance while reducing the coil radius Now, compare dense W HCAL with analog (scintillator) and digital (RPC) readout modes (same depth - 4 λ I )

17 New Detector Models based on SD Design Dense HCALs (W absorber) - 4 λi in ~82.5 cm IR -> OR SDFeb05 SCI HCAL 55 layers of 0.7 cm W/0.8 cm Scin. Sampling fraction ~6% SDFeb05 RPC HCAL 55 layers of 0.7 cm W/0.8 cm RPC 1.2 mm gas gap Sampling Fraction ~0.0025%!!!

18 First Calorimeter Performances Scin. Analog Readout RPC Digital Readout Hard to compete with no visible energy? Not a great start, but lets continue anyway

19 Track/CAL Cell Association Algorithm Scin. Analog Readout RPC Digital Readout Resolution still better in scintillator, but algorithm reproduces perfect ID in both cases

20 Neutral Finding Algorithm Scin. Analog Readout RPC Digital Readout Once again, very similar performance

21 PFA Results Scin. Analog Readout RPC Digital Readout PFA performance is very similar (with same cuts) but reflects underlying CAL resolution

22 Confusion Leftover Hits! Scin. Analog Readout RPC Digital Readout Better use of hits in RPC? good since aren t that many

23 PFA Improvements Neutral Clustering Neutral Clustering No Neutral Clustering

24 DiJet Mass from PFA Scin. Analog Readout RPC Digital Readout

25 Summary For LC Detector, HCAL should be as dense as possible -> more λ I per cm smaller Solenoid B-field volume -> more layers for fixed total λ I HCAL better resolution since more sampling -> more hits - better digital resolution -> more visible E better analog resolution Comparing W and SS absorbers, hadron showers appear to be smaller (rms of E distribution) in W -> results in improvement of PFA analysis Beginning systematic studies of readout modes, absorber types and thickness for HCAL using flexibility of XML detector geometry description should result in optimization of both the LC Calorimeter and its associated PFA analysis method.

26 W Absorber HCAL for Test Beam For 95% containment of a 5(10) GeV pion shower : Rπ(95%) = 2( ln E) in λ I = 1.10 λ I (1.14 λ I ) transverse to beam Lπ(95%) = ln E in λ I = 3.81 λ I (4.9 λ I ) along beam So, for 0.7 cm W/0.5 cm Scin each layer : Need 22 cm x 22 cm transverse to beam, and 52 (67) layers along the beam HCAL standalone -> 25K (32K) readout channels 41 (56) layers along the beam with ECAL -> 20K (27K) readout channels For 2 cm SS/0.5 cm Scin each layer : Need 38 x 38 cm transverse to beam, and 32 (41) layers along the beam HCAL standalone -> 46K (59K) readout channels 25 (34) layers along the beam with ECAL -> 36K (49K) readout channels

27 This page intentionally left blank

28 SD Detector a Particle-flow Detector for the LC Tracking : Multi-layer Si Vertex Detector ~1 cm -> ~7 cm radius, 5 layers Si-Strip Tracker ~20 cm -> ~1.25 m radius, 5 layers ECAL : 30 layers, ~1.25 m -> ~1.40 m radius W(0.25 cm)/si(0.04 cm) ~20 X 0, 0.8 λ I ~5 mm X 5 mm cells HCAL : 34 layers, ~1.45 m -> ~2.50 m radius SS(2.0 cm)/scin(1.0 cm) ~40 X 0, 4 λ I ~1 cm X 1 cm cells Solenoid Coil : 5 Tesla, ~2.50 m -> ~3.30 m radius Muon (Tail Catcher) : ~3.40 m -> ~5.45 m

29 Motivation for Track-First P-FlowP Charged particles ~ 62% of jet energy -> Tracker σ/p T ~ 5 X 10-5 p T ~190 MeV to 100 GeV jet energy resolution Photons ~ 25% of jet energy -> ECAL σ/e ~ 15-20%/ E ~900 MeV to energy resolution Neutral Hadrons ~ 13% of jet energy -> HCAL resolution not critical ~3 GeV to energy resolution Also, since ECAL is dense, hadrons are optimally separated from photons (starting point of shower longitudinally) -> 75% of hadrons shower after photon shower-max in ECAL

30 Shower reconstruction by track extrapolation ECAL HCAL Mip reconstruction : Extrapolate track through CAL layer-by-layer Search for Interaction Layer -> Clean region for photons (ECAL) track mips IL shower Shower reconstruction : Define cones for shower in ECAL, HCAL after IL Optimize, iterating cones in E,HCAL separately (E/p test)

31 e+e- -> > Z (jets) First Interaction Layer SS W 14 more layers 30 more layers 60 cm into SS HCAL 42 cm into W HCAL

32 e+e- -> > Z (jets) Linearity of Energy Response SS W Both exhibit linear analog response

33 e+e- -> > Z (jets) Linearity of Hit Response SS W Both exhibit linear behavior for number of hits vs energy -> more hits per GeV (vis E) in W (same as for single pion)

34 PFA Development Status True vs Current PFA True PFA (no confusion) -> 28%/ E Current PFA Status 35%/ E (conical showers) 70%/ E (needs work!*) * Improved with better neutral reconstruction